dupe n.

"stupid person," 1590s, from Spanish bobo "stupid person," also used of various ungainly seabirds, probably from Latin balbus "stammering," from an imitative root (see barbarian).

The specific sense "dunce in a school class" is by 1825. Hence also booby prize "object of little value given to the loser of a game," attested by 1884:

At the end of every session the dominie had the satirical custom of presenting his tawse [a corporal punishment implement used for educational discipline] as a "booby-prize" to some idle or stupid lout whom he picked out as meriting this distinction so that next time they met he might start fresh and fair with new pair for a new set of classes. [Ascott R. Hope, "Dumps," Young England magazine, September 1884]

Booby trap is by 1850, originally a schoolboy prank; the more lethal sense developed during World War I. Booby-hatch "wooden framework used to cover the after-hatch on merchant vessels" is from 1840; as "insane asylum" by 1936.

"a large waterfowl proverbially noted, I know not why, for foolishness" [Johnson], Old English gos "a goose," from Proto-Germanic *gans- "goose" (source also of Old Frisian gos, Old Norse gas, Old High German gans, German Gans "goose"), from PIE *ghans- (source also of Sanskrit hamsah (masc.), hansi (fem.), "goose, swan;" Greek khen; Latin anser; Polish gęś "goose;" Lithuanian žąsis "goose;" Old Irish geiss "swan"), probably imitative of its honking.

Geese are technically distinguished from swans and from ducks by the combination of feathered lores, reticulate tarsi, stout bill high at the base, and simple hind toe. [Century Dictionary]

Spanish ganso "goose" is from a Germanic source. Loss of "n" sound before "s" is normal in English (compare tooth). Plural form geese is an example of i-mutation. Meaning "simpleton, silly or foolish person" is from early 15c. To cook (one's) goose is attested by 1845, of unknown origin; attempts to connect it to Swedish history and Greek fables are unconvincing. Goose-egg "zero" is attested by 1866 in baseball slang, from being large and round. The goose that lays golden eggs (15c.) is from Aesop.

cant term for "dupe, sucker, credulous person," 1590s, of uncertain origin. Perhaps from verb meaning "to dupe, cheat" (see gull (v.)). Or it is perhaps from (or influenced by) the bird name (see gull (n.1)); in either case with a sense of "someone who will swallow anything thrown at him." Another possibility is Middle English gull, goll "newly hatched bird" (late 14c.), which is perhaps from Old Norse golr "yellow," from the hue of its down.